Method to increase head voltage swing and to reduce the rise time of write driver

Abstract

A voltage-mode boosting write driver circuit () having a pair of voltage boosting PMOS transistor sets () coupled to a high current H-switch (). One set () of the boosting PMOS transistors correspondingly pulls output pin HY high, while the other transistor set () correspondingly pulls output pin HX high and the other output pin HY low thereby significantly improving the head voltage swing, and also achieving a faster slew rate. Moreover, resistors (R, R) of the H-switch are both matched to each other and impedance matched to a flex cable (T) interconnection impedance, which interconnection is coupled to the thin film head, to thereby eliminate signal reflection such that the write current (Iw) settles quickly with minimum ringing to achieve a high data rate. Moreover, less power dissipation and smaller number of devices used are achieved by making use of existing transient currents of the pre-driver emitter follower stage.